1. Field of the Invention
The present invention relates to a photovoltaic device, and more particularly, it relates to a photovoltaic device comprising a photovoltaic element including a transparent conductive oxide film and a paste electrode formed thereon.
2. Description of the Background Art
A photovoltaic element having a structure obtained by inserting a substantially intrinsic amorphous semiconductor layer between a fist conductivity type crystalline semiconductor layer and a second conductivity type amorphous semiconductor layer thereby improving junction characteristics and comprising a transparent conductive oxide film formed on the second conductivity type amorphous semiconductor layer and a paste electrode formed thereon is known in general. For example, Japanese Patent Laying-Open No. 2003-197943 discloses this type of photovoltaic element.
According to the structure of the aforementioned photovoltaic element disclosed in Japanese Patent Laying-Open No. 2003-197943, amorphous semiconductor layers can be formed by plasma CVD at a low temperature of not more than about 200° C. When the photovoltaic element is formed through such a low-temperature process, a paste electrode is formed on a transparent conductive oxide film with low-temperature fired paste hardenable by firing at a temperature of not more than about 200° C.
In the structure of the aforementioned photovoltaic element disclosed in Japanese Patent Laying-Open No. 2003-197943, however, relatively small adhesiveness of the low-temperature fired paste to the transparent conductive oxide film may reduce adhesiveness of the paste electrode to the transparent conductive oxide film. If external force is applied to the paste electrode through an electric wire when a photovoltaic device (photovoltaic module) is prepared by connecting a plurality of photovoltaic elements having such paste electrodes with each other through the electric wire, therefore, the electric wire and the paste electrode may separate from the transparent conductive oxide film of the photovoltaic element. Consequently, the yield in production of the photovoltaic device is disadvantageously reduced.